There is known a slip ring device in which a ring member is provided upon a rotation shaft, at least one brush is pressed against the ring member, and exchange of electrical power or of electrical signals between these components is performed. As such slip ring device, there is known an apparatus in which the ring member and the brush are housed within a housing member whose surrounding wall is provided with a plurality of ventilation holes for heat dissipation (see Patent Literature 1). In addition, there are Patent Literatures 2, 3 as prior art references in relation to the present invention.